Based on advances in both our own work and confirming work of others, we are continuing to investigate the following areas: The origin of antibody diversity - cloned hybridoma cell lines producing the lambda 1 light chain are being studied to determine the exact rules of amino acid replacement in complementarity-determining residues (CDR's). In addition, the ability of any particular VL to pair with the repertoire of VH's is being examined. Genetic mapping of loci important in immune system functioning - using recombinant-inbred (RI) strains (BALB/c x SJL)RI we have constructed, we are beginning to map the genetic loci for several immune system functions related to various pathological states, lambda lo, IgE responsiveness, B-lymphocyte colony forming cells in the thymus, frequency of reticulum cell sarcoma (mouse model for Hodgkins), oil-induced myelomas, etc. The mechanism of cell-cell interaction - the identity of the so-called antigen-presenting cell is being investigated with respect to its markers and origin; the restriction of suppressor T-cells is being mapped; cell-lines which are antigen-sensitive and representative of all of the classes of t- and B-cells are being isolated; the inductive transmitter signal delivered to antigen-sensitive cells interacting with antigen is being sought.